Created by ChanaBen-Ezra on July 8, 2015
Step 1: Peel potatoes, then mash the potatoes in a large stand mixer until very smooth.
Step 2: Melt the shortening in a skillet over high heat and saute the onions until lightly browned. Set aside.
Step 3: Drain the mushrooms and briefly saute them in the remaining shortening.
Step 4: Mix the mashed potatoes, sauteed onions, and sauteed mushrooms, then season mixture with salt and pepper.
Step 5: Cool mixture to almost room temperature before using.